There are many plants in the lavender family, but the type most commonly used medicinally is English lavender.

Traditionally, the
essential oil of lavender was applied externally to treat joint pain, muscle aches, and a variety of skin conditions, including insect stings, acne, eczema, and burns. Lavender essential oil was also inhaled to relieve headaches, anxiety, and stress. Tincture of lavender was taken by mouth for joint pain, depression, migraines, indigestion, and anxiety.

Lavender was additionally used as a hair rinse and as a fragrance in “dream pillows” and potpourris.

Lavender continues to be recommended for all its traditional uses. Only a few of these uses, however, have any supporting scientific evidence whatsoever, and for none of these is the evidence strong.

A few studies suggest that lavender oil, when taken by inhalation (
aromatherapy ) might reduce agitation in people with severe
dementia . For example, in one very well-designed but very small study, a hospital ward was suffused with either lavender oil or water for two hours.
1 An investigator who was unaware of the study’s design and who wore a device to block inhalation of odors entered the ward and evaluated the behavior of the 15 residents, all of whom had dementia. The results indicated that use of lavender oil aromatherapy modestly decreased agitated behavior. A somewhat...

Safety

No form of lavender has undergone comprehensive safety testing.

Internal use of lavender essential oil is unsafe and should be avoided. Topical use is considered much safer. Allergic reactions are relatively common, as with all essential oils. In addition, one case report suggests that a combination of lavender oil and
tea tree oil applied topically caused gynecomastia (breast enlargement) in 3 young boys.
2
A controlled study found that inhalation of lavender essential oil might impair some aspects of mental function.
3 (Presumably, this was due to the intended sedative effects of the treatment.)

Oral use of tincture of lavender has not been associated with any severe adverse effects, but comprehensive safety testing has not been performed.